1. Field of the Invention
This invention relates to a machine of the type placed on the ground which holds a series of pots linked together and each containing a seedling grown therein, and delivers the pots one after another from one end thereof for transplantation without separating the pots from one another, or from the seedlings.
2. Description of the Prior Art
A method which is widely used for transplanting seedlings employs square or hexagonal pots made of a thin material, such as paper. The pots are filled with soil, seeds are sown in the soil, seedlings are grown from the seeds under controlled sprinkling of water, and the potted seedlings are transplanted to a patch. There are two types of pots as classified by use for transplantation. A multiplicity of pots linked together for growing seedlings are separated into the individual pots prior to transplantation as disclosed in Japanese Patent Publication No. 25715/1963, or are supplied for transplantation in a chain without being separated from one another as disclosed in Japanese Patent Publication No. 30805/1980.
The decrease of manual labor has recently become essential in agriculture, too, as a result of the decrease in agricultural population, and the advance of ages of people engaging in agriculture. In this connection, the successive transplantation of seedlings by the latter type of pots has drawn attention, as it enables the fully automatic transplantation of seedlings by a machine.
There are known a number of transplanting machines. For example, Japanese Patent Publication No. 30805/1980 discloses a transplanting machine which includes two pairs of rotating members for holding two successive pots, respectively, which are linked together by a connecting material having a cut formed therein. The rotating members holding the preceding pot are rotated at a peripheral speed which is higher than that of the rotating members holding the following pot, whereby the connecting material is pulled and torn apart at its cut to enable the pots to be separated from each other for transplantation.
Japanese Patent Publication No. 61866/1988 discloses a transplating machine which includes a rotating disk having radially extending transplanting rods for holding a pot therebetween. When the disk is rotated to move the pot forward, a stop member is caused to act upon another, or the following pot linked to the preceding pot by a connecting material having a cut formed therein, whereby the connecting material is pulled and torn apart at its cut to enable the pots to be separated from each other for transplantation.
Japanese Patent Publication No. 28321/1979 discloses a series of pots linked together by a different connecting material having no such cut as described above. It is a decay-resistant string bonded to the centers of every two adjoining pots by a water-resistant paste, and having between every two adjoining pots a loose length which is equal to the distance between the seedlings to be transplanted. The string links the pots together in a multiplicity of rows, and every two adjoining rows of pots are bonded to each other by a water-soluble paste. The same publication also discloses a transplanting machine of the traction type which is movable on wheels contacting the ground for delivering the pots one after another from a platform, while allowing the string to be stretched between every two adjoining pots, and transplanting the potted seedlings successively without separating the pots from one another in the soil dug by a soil opener attached to the rear end of the platform.
The known machines, however, have drawbacks. The machine disclosed in Japanese Patent Publication No. 30805/1980 is adapted for handling relatively small pots and transplanting potted seedlings, such as of beets, at a spacing of 23 to 25 cm. The machine disclosed in Japanese Patent Publication No. 61866/1988 is adapted for handling relatively large pots and transplanting potted seedlings, such as of lettuce or cabbage, at a spacing of 30 to 45 cm. These machines are capable of transplanting potted seedlings at a spacing which is not smaller than, say, 10 cm, and are, therefore, incapable of transplanting potted seedlings of vegetables such as spinach and garland chrysanthemums, for which a transplanting spacing of 4 to 8 cm is usually appropriate. Moreover, a still smaller and simpler machine is desired for transplanting potted seedlings in a small area of land, as in a greenhouse.
The machine disclosed in Japanese Patent Publication No. 28321/1979 has a high platform level due to its wheels. Therefore, it is suitable for transplanting potted seedlings linked together by a loose and flexible material such as the string described above, but is not suitable for handling pots linked together by a material which forms an integral part of the pots, and is not loose or flexible, as disclosed in Japanese Patent Publication No. 30805/1980, since there is a limit to the angle at which the pots can properly be delivered from the platform to the ground. Any attempt to deliver the pots at a greater angle is very likely to cause the falling down of the pots or the breakage of the connecting material, and result in the interruption of any further delivery of the pots and thereby of transplantation work. The delivery of the pots within the limited angle is not always satisfactory, since it is likely that, as each pot is required to travel a longer distance from the high platform level to the ground, it may show a greater resistance to movement and thereby cause the connecting material to break.